In a conventional image forming apparatus, a drum and process means actable on the drum are unified into a cartridge which is detachably mountable to a main assembly of the apparatus (process cartridge type).
With such a process cartridge type, maintenance operations for the image forming apparatus can be performed in effect by the user without relying on a service person, and therefore, the operationality can be remarkably improved. Therefore, the process cartridge type is widely used in the field of the image forming apparatus.
A process cartridge (Japanese Laid-open Patent Application 2001-337511), for example) and an image forming apparatus (Japanese Laid-open Patent Application 2003-208024, for example) have been proposed, in which a clutch is provided to effect switching to drive the developing roller during an image forming operation and to shut off the drive of the developing roller during a non-image-formation.